iOS: If you don't have unlimited data, or haven't found a way around that problem, you need to stay within your limit to avoid overage charges. The easiest way to do that is to track what you do, and My Data Usage Pro can help you do that.

Today, Verizon has officially ended its unlimited data plan, joining several other carriers in an…
Read more Read more

To get started, launch My Data Usage Pro (which we're going to call MDUP from here on out) and set your limits for the month as well as the day your month starts on (as billing cycles tend to vary. Once you do, just use your iDevice as normal and it'll keep track of the data you use. Just launch the app to check how much cellular and Wi-Fi data you're using. MDUP is really simple and does the job well. The only additional feature that would be particularly handy is if you could set alerts to tell you when you're getting close to exceeding your data caps.

MDUP is a hybrid app, meaning you get a copy that works natively on your iPhone/iPod touch and iPad.